Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC

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000
FXUS62 KRAH 301908
AFDRAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RALEIGH NC
304 PM EDT TUE JUN 30 2015

.SYNOPSIS...AN INCREASINGLY ACTIVE CYCLONIC FLOW ALOFT WILL PREVAIL
OVER THE REGION THROUGH THE END OF THE WORK WEEK.

&&

.NEAR TERM /TODAY AND TONIGHT/...
AS OF 300 PM TUESDAY...

THE WESTERN HALF OF THE CWA CONTINUES TO BE UNDER A SLIGHT RISK FOR
SEVERE THUNDERSTORMS WITH DAMAGING WINDS THE MOST LIKELY THREAT. THE
SPC HAS ISSUED A MESOSCALE DISCUSSION FOR CENTRAL NC AND INDICATES
THAT A SEVERE THUNDERSTORM WATCH IS POSSIBLE LATER THIS
AFTERNOON/EVENING BUT IT IS UNCLEAR AT THIS TIME HOW CONVECTION
ENTERING UPSTATE SOUTH CAROLINA WILL EVOLVE. SEVERE STORMS ARE
CURRENTLY ONGOING IN THIS AREA WITH SEVERAL REPORTS OF WIND DAMAGE
ALREADY.

WITH A ROBUST SHORTWAVE SUPPLYING THE VORTICITY AND UPPER DIVERGENCE
BEING HELPED BY AN EXITING JET TO THE NORTHEAST...EFFECTIVE SHEAR IN
THE AREA OF CONVECTION HAS BEEN AROUND 30-35 KTS WITH MULTI CELLULAR
CONVECTION STARTING TO EVOLVE INTO LINE SEGMENTS AS OF LAST HOUR.
THIS AMOUNT OF SHEAR IS EXPECTED TO BE MAINTAINED OVER THE NEXT
SEVERAL HOURS BEFORE WEAKENING SLIGHTLY AROUND 00Z. A LOT OF THIS
SHEAR IS WELL OFF THE DECK AND LOW LEVEL SHEAR AND HELICITY VALUES
ARE FAIRLY LOW DURING THE TIME OF CONVECTION LIMITING THE TORNADO
THREAT. ON THE INSTABILITY SIDE OF THINGS...CONVECTION WILL BE
MOVING INTO AN AREA OF 1000-1500 J/KG OF MIXED LAYER CAPE AND
BRINGING WITH IT AN AREA OF 1200-1400 J/KG OF DCAPE. LOW LEVEL LAPSE
RATES AT THIS TIME ARE VERY HIGH WITH A MODERATE 6 DEG/KM OR SO IN
THE MID-LEVELS. WITH CURRENT CONVECTION ALREADY ORGANIZING IT IS NOT
HARD TO ENVISION IT HANGING TOGETHER AS THE VORT MAX MAKES ITS WAY
UP THE PIEDMONT TROUGH. WHILE DIURNAL TIMING MAY NOT YIELD QUITE AS
GOOD OF AN ENVIRONMENT AS THE STORMS ARE CURRENTLY IN...CONFIDENCE
IS FAIRLY GOOD THAT AT LEAST SOME ACTIVITY WILL MOVE INTO THE CWA
FROM THE SOUTHWEST AND PROPAGATE ACROSS THE CWA EXITING SOMETIME
AFTER 5Z OR SO ON WEDNESDAY MORNING. EXPECT THE BEST CHANCE FOR
STRONGER CONVECTION ACROSS THE SOUTHWEST PIEDMONT AND INTO THE
WESTERN SANDHILLS BEFORE STARTING TO WEAKEN AS IT HEADS NORTHEAST.
CONVECTION IS POSSIBLE IN THE TRIAD AS WELL AS ANOTHER LINE OF
STORMS IS BEGINNING TO POP UP ALONG THE FOOTHILLS. ALL OF THIS
ACTIVITY SHOULD TRANSLATE EASTWARD. WHILE THE TRIANGLE MAY NOT GET
THE BRUNT OF THE ACTIVITY...STRONG STORMS ARE CERTAINLY POSSIBLE IN
THIS AREA AS WELL BUT MIGHT BE ON THE NORTHERN FRINGE OF THE
STRONGER ACTIVITY.

OVERNIGHT TONIGHT SKIES SHOULD BEGIN TO CLEAR OUT WITH AN OUTSIDE
CHANCE OF SOME FOG/LOW STRATUS EXISTS IN THE EAST WITH LOWS MID 60S
TO LOWER 70S.

&&

.SHORT TERM /WEDNESDAY AND WEDNESDAY NIGHT/...
AS OF 300 PM TUESDAY...

ON WEDNESDAY THE UPPER LEVEL TROUGH OVER THE EASTERN CONUS RELAXES A
LITTLE AND A STRONG SURFACE LOW EXITS THE GREAT LAKES REGION TO THE
NORTHEAST AND MOVES INTO SOUTHERN ONTARIO. WITH A GAP IN THE
MOISTURE BEHIND THIS SYSTEM AND AHEAD OF WHAT WILL BE A STRING OF
APPROACHING SHORTWAVES FROM THE MIDWEST...LOOK FOR A RELATIVELY DRY
DAY ON WEDNESDAY WITH AN ISOLATED DIURNAL SHOWER OR THUNDERSTORM
POSSIBLE BUT OTHERWISE DRY. WITH THE BERMUDA HIGH FORCED OFF THE
COAST AND CENTRAL NC SITTING AT THE BASE OF THE UPPER
TROUGH...TEMPERATURES WILL STAY FAIRLY REASONABLE FOR THIS TIME OF
YEAR WITH HIGHS IN THE UPPER 80S NW TO LOW 90S SE. FORECAST
SOUNDINGS DO NOT INDICATE MUCH CHANCE FOR FOG OR LOW STRATUS
THURSDAY MORNING BUT A BROKEN LOW CEILING IS NOT OUT OF THE QUESTION
IN THE EAST BUT CONFIDENCE IN THAT HAPPENING IS VERY LOW AT THIS
TIME.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
AS OF 300 PM TUESDAY...

THE GENERAL OVERALL PATTERN WILL BE DOMINATED BY GENERAL TROUGHINESS
IN THE UPPER LEVELS OVER THE EASTERN U.S. WITH A FEW SHORTWAVE
DISTURBANCES PROGRESSING THROUGH THE AREA. AT THE SURFACE...A WARM
FRONT WILL LIFT NORTH THROUGH NC THURSDAY NIGHT INTO FRIDAY. EXPECT
GENERAL LOW PRESSURE TO LINGER OVER THE SOUTHEAST U.S. AND HIGH
PRESSURE STUCK OVER THE EASTERN GREAT LAKES AND NEW ENGLAND
THEREAFTER. SMALL VARIATIONS IN THIS PATTERN WILL HAVE BIG IMPACTS
ON THE CHANCES...TIMING...AND LOCATION OF CONVECTION...THUS
CONFIDENCE IS NOT TERRIBLY HIGH IN THAT RESPECT. GENERALLY THOUGH...
EXPECT THE USUAL HIGHEST CHANCES IN THE AFT/EVE AND LOWEST
OVERNIGHT/EARLY MORNING. TEMPERATURE WISE: WITH THE EXCEPTION OF
FRIDAY (WHICH FOR NOW APPEARS TO BE THE COOLEST DAY)...HIGHS WILL
GENERALLY BE IN THE UPPER 80S TO LOW 90S THROUGH THE PERIOD...WITH
OVERNIGHT LOWS STEADY IN THE UPPER 60S TO LOW 70S TO SLIGHTLY
INCREASING EARLY NEXT WEEK.

&&

.AVIATION /18Z TUESDAY THROUGH MONDAY/...
AS OF 200 PM TUESDAY...

24 HOUR TAF PERIOD: VFR CONDITIONS PREVAILING ACROSS THE CWA THIS
AFTERNOON WITH STRATOCUMULUS STARTING TO ENCROACH FROM THE WEST AS A
SHORTWAVE APPROACHES FROM THE SOUTHWEST. WINDS WILL BE VARIABLE AT
TIMES THIS AFTERNOON BUT GENERALLY 5-10 KTS AND WITH A SOUTHWESTERLY
COMPONENT. SOME WIND GUSTS OF AROUND 15-20 KTS WILL CONTINUE THROUGH
SUNSET BEFORE DISSIPATING. A LINE OF CONVECTION MOVING INTO UPSTATE
SOUTH CAROLINA WILL CONTINUE TO DEVELOP TO THE NORTHEAST AND TRACK
ACROSS THE AREA THIS EVENING. WHILE THERE IS GREAT UNCERTAINTY
WHETHER OR NOT STRONGER STORMS WILL AFFECT THE TRIAD AIRPORTS TIMING
FOR AT LEAST SOME SHOWERS IN THIS AREA WILL BE BETWEEN 21Z AND 00Z.
A RAGGED LINE OF STORMS COULD PROGRESS EASTWARD THROUGH THE EVENING
AFFECTING KRDU AND KFAY AROUND 00Z AND PROGRESSING EASTWARD OUT OF
THE CWA BY 5Z AT THE LATEST. SOME SEVERE STORMS ARE POSSIBLE IN THIS
LINE WITH DAMAGING WINDS THE MOST LIKELY THREAT. AFTER STORMS EXIT
TO THE EAST...EXPECT SOME GENERAL CLEARING WITH SOME FOG/LOW STRATUS
POSSIBLE...ESPECIALLY AT THE EASTERN 3 TERMINALS. THIS WILL
DISSIPATE AT OR SHORTLY AFTER SUNRISE AND CONDITIONS WILL RETURN TO
VFR. WE CAN EXPECT MOSTLY CLEAR SKIES AND SOUTHWESTERLY WINDS
THROUGH THE END OF THE TAF PERIOD.

LONG TERM: CENTRAL NC IS SETTING UP TO BE IN A FAIRLY ACTIVE AND
UNSETTLED PATTERN FOR THE NEXT SEVERAL DAYS WITH PERIODS OF ADVERSE
CONDITIONS POSSIBLE THROUGH EARLY NEXT WEEK.

&&

..RAH WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$

SYNOPSIS...VINCENT
NEAR TERM...ELLIS
SHORT TERM...ELLIS
LONG TERM...RAH
AVIATION...ELLIS


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